End cap for gaseous discharge lamps



Oct. 9, 1945. M. D. BETTS END CAP FOR GASEOUS DISCHARGE LAMPS Filed July 10, 1944 INVENTOR.

- ATTORNEY m w B w D H of the lamp taken on line Patented Oct. 9, 1945 PATENT OFFICE END CAP FOR GASEOUS DISCHARGE LAMP Mazeppa Don Betta, Rockport, Mass assignor to *Sylvania Electric Products Inc., Salem, Mara,

a corporation of Massachusetts Application July 10,

2 Claims.

This invention relates to end caps for gaseous electric discharge lamps and more particularly to a means for rigidly uniting the caps and the lamps.

It has been found that cements which are suit= able in all other respects do not effectively adhere to certain metal coatings employed to protect ferrous metals from corrosion. An example of such a coating is a zinc plating upon sheet steel. When this coated metal is used as a substitute for brass for example, it has been difiicult to obtain a firm union between the lamp end and the cap.

The present invention supplies means for correcting the weakness in such a union. Briefly stated, the invention lies in providing means to supplement the holding power of the cement by providing a novel construction which mechanically interlocks the cement with the end cap assembly thus adding the shear strength of a substantial portion of the cement to the strength of the union.

An object of the invention is'to provide a. construction which will reinforce the union between the lamp end and the end cap assembly,

A further object of the invention is to provide a. union between the lamp and its end cap which is partially independent of the power of adhesion between the cement used and the interengaging surfaces.

Other objects and features of the invention will more fully appear from the following description in connection with the accompanying drawing and will be particularly pointed out in the claims.

In the drawing:

Figure 1 is a perspective view of one end of a gaseous discharge lamp embodying the invention;

Figure 2 is a cross section through the end cap 2-2, Figure 4; Figure 3 is a cross section on line 3-8, Figure 4; and

Figure 4 is an inside view of an end cap before it is assembled to the lamp.

To present a better understanding of the invention a particular embodiment thereof will now be described. The embodiment illustrated is applied to an elongated tubulartype of lamp but may be applied to other types of lamps. The lamp envelope 5 is provided with an end cap assembly 6 at both ends. The body I of the end cap is of metal. The metal used may be selected for economy in cost or for any other reason such as lack of availability. Heretofore, the metal 1944, Serial No. 544,206

disadvantage the present invention supplies means for reinforcing the union between the envelope and the cap by supplementing the adhesion of the cement to the metal.

The metallic body member I is cup shaped having a flange 8 which embraces the end of the glass envelope and an end wall s-from which the central portion has been removed to present an opening Iii therein. A pair of superposed wafers H and I! of insulating material are received in the body member I, the outer one \ofv which engages the wall 9 and is rigidly secured within the body member by crimping or knurling the adjacent portion of the flange 8 into intimate engagement with the peripheral edge of the wafer II as at I! thereby locking the two elements together. The wafer l2 lies over the wafer II and is slightly less in diameter. The teeth upset in the metal by the knurling operation indent and interlock with the peripheral edge of the wafer I2 thus increasing the bond between it and the member 1.

A pair of contact pins H are received in registering apertures IS in the' wafers II and i2. Each of the pins are provided with upset collar portions i6 engaging the wafer ii and having their inner ends swaged or riveted into contact with the wafer l2 thus rigidly fixing the pins in position and also securing the two wafers to- 40 gether. The wafer i2 is thus also rigidly secured to the cap assembly through the pins it which pass through the wafer ii. The cap is shown as having two pins. However, any number of pins may be used depending upon the type of lamp being manufactured. The wafer l2 has formed therein a plurality of recesses or notches i'l preferably near its periphery.

As shown in Figure 3 the end extremity of the envelope is tapered inward and has fused thereto the stem assembly 19 of the lamp as is usual in this type of lamp. The main body of the cement, which is of the filler type, is forced into the chamber 20 between the flange 8 and the envelope 5 where it adheres strongly to the glass envelope. The lack of a firm adherence between the cement and th metal body member is compensated for by the fact thatsome or the cement flows into the recesses I1. There is also considerable adhesive force between the cement and the wafers II and i2. When the cement hardens therefore, it interlocks the end cap to the main body of the cement thus preventing possible relative rotation between the end cap and the lamp envelope as well as preventing endwise looseness and possible detachment of the cap.

What I claim is:

1. An end cap construction for gaseous discharge lamps having a glass envelope, comprising a cup shaped metallic body member extending over the end portion of the envelope, 9; pair 01 superposed insulating wafers within the body member, which are rigidly anchored to the end wall of said body member, a plurality of contact pins projecting through and secured in both of said wafers, one or more recesses in the innermost wafer, a quantity of filler cement between the end portion of said envelope and the flange of of the envelope, a pair of superposed insulating waters which are rigidly anchored to the said end wall, a plurality of contact pins extending through and anchored in both of said wafers, recesses in the innermost oi said wafers. a quantity of flller cement between the end portion of said envelope and the flange of said body member said cement adhering to the end of said envelope and extending into the recesses in said water whereby a flrm connection is established between 20 the said envelope and the end cap assembly.

M. DON BETTE. 

